Apparatus for hydraulic control of the transverse sealing jaws of a packaging machine



Aug. 16, 1966 G. VAN DEN 805 APPARATUS FOR HYDRAULIC CONTROL OF THETRANSVERSE SEALING JAWS OF A PACKAGING MACHINE Filed Dec. 19, 1963 INVEN TOR: ER/PIT WW DEN B05 BY United States Patent 3,266,217 APPARATUSFOR HYDRAULEC CGNTRGL OF THE TRANSVERSE SEALENG .lAWS 6F A PACKAG- INGMACHlNE Gerrit van den Bus, Weert, Netherlands, assignor toHamac-Hansella Aktiengesellschaft, Viersen, Germany, a corporation ofGermany Filed Dec. 19, 1963, er. No. 331,664 Claims priority,application Germany, July 19, 1963, H 49,763 11 Claims. (Cl. 533-480}This invention relates to an apparatus for hydraulically closing thetransverse sealing jaws of a packaging machine of the type in which atube of packaging material is advanced by such jaws in an intermittentfashion to bring successive regions to a filling position and to sealoff such regions after they have been filled.

In machines of this kind, the jaws are movable toward and away from eachother and also in an up-and-down direction. They are operated so as tocome together at the upper end of their travel, thus engaging the tubeabove the region just filled; then they move downwardly to draw the tubedown through a predetermined distance; then they separate and travelupward so that the procedure can be repeated. During each period of restof the tube, the items to be packaged are introduced into the tube fromabove to fill the tubular part that has been pulled down. When the jawscome together they form a top seal on the filled portion, and may cut itoff to form a filled bag. At the same time, the bottom seal of the nexttube portion is produced.

An object of the invention is to provide an improved hydraulic mechanismfor controlling the movements of the jaws toward each other, and bymeans of which the speed of operation and thereby the output of thepackaging machine can be increased, and the idling ope-ration of themachine improved, thereby reducing wear and tear.

According to the invention the apparatus involves two opposed hydrauliccylinders on whose pistons the sealing jaws are mounted in opposedrelationship, the cylinders being actuated by a pumped pressure fluid,the pump being a piston pump driven in timed relation to the packagingprocedure. The device is characterized by a communication between thepump and a special cylinder with which a pressure-regulating valve isassociated; and by an auxiliary pump and a regulating valve which feedextra pressure fluid into the first-mentioned piston pump at the instantof the commencement of the suction or return stroke of the latter.

In accordance with one of the features of the invention, thelast-mentioned regulating valve has a cylindrical bore in which arotating :plug is mounted for rotative movements in timed relation tothe packaging procedure. There is an annular groove in the cylindricalbore which is in constant communication with the auxiliary pump. Thereis also a communication between the regulating valve and the mainpressure-fluid piston pump, this communication leading to thecylindrical bore referred to. On the rotating plug there is a groove orcut-out which connects the last-mentioned communication with the annulargroove previously referred to at predetermined positions of the plugduring the course of its rotative movements.

Further details of the invention will become clear from the followingdescription of a preferred embodiment of the invention, and referenceshould be made to the accompanying drawing in which the apparatus isschematically depicted.

The reference numeral 1 is directed to a schematic rep resentation ofthe transverse sealing jaws of a packaging machine of the charactermentioned. These jaws are se- 3,266,217 Patented August 16, 1966 curedto the piston rods of two pistons 22 mounted in opposed relationship influid pressure cylinders 2. Between the pistons and the forward ends ofthe cylinders compression springs 3 are arranged, designed to open thejaws 1 against the action of the pressure fluid, preferably oil. Inplace of the springs 3, tension springs arranged on the exterior of thecylinders could be used for the same purpose.

The cylinders 2 are in communication with each other via the pipe orconduit 4. A pressure regulating unit 9 is also in communication withthe pipe 4. The unit 9 consists of a cylinder in which a piston 93 ismounted. A pipe extends from one end of the cylinder to the pipe 4. Aspring 92 presses at one end against the piston 93 and bears with itsother end against an adjusting device 911 which can be projected intothe cylinder 9 by varying amounts by screwing it or unscrewing it withrespect to the cylinder wall. In this way, a predetermined springpressure can be exerted against the piston, variable at will.

The arrangement is so designed that the stroke-volume of the piston 8 issomewhat greater than that of the combined pistons 22, as a result ofwhich the piston 93 a ways exerts a predetermined pressure against thespring 92. Thus, the pressure in the system, and thus the pressurebetween the jaws 1, is determined by the adjustable spring pressureagainst the piston 93.

A communication 5 extends from pipe 4 to fluid pressure pump 6. The pump'6 is, in the illustrated embodiment, shown as a piston pump. The piston8 has a piston rod 82 on whose end a cam follower 77 is mounted, hearingagainst the eccentric disk 7. The latter is driven in the direction ofthe arrow by means of the driving mechanism of the packaging machine. Asthe follower 77 rolls on the periphery of the eccentric disk 7 thepiston 8 is caused to partake of a reciprocating motion within thecylinder 6. A spring 81 is mounted in this cylinder and urges the pistonconstantly upward, thus holding the follower 77 against the periphery ofthe disk. 7. The spring 31 is by itself insulficient for this purpose;it is aided by the springs 3 (via the oil pressure) and by the oiltransmitted to it by means of the pump 11.

On the pressure side of the pump 6 there is a safety valve 18,illustrated in the form of a ball valve whose ball 181 is pressed by aspring 182 against its seat. A communication 183 leads to the oilreservoir.

The pump 6 is also in constant communication, by a pipe 10, with aregulating valve 14. The fixed block 141 of this valve has a centralcylindrical bore 142 in which a rotatable plug 16 is mounted. This plugis rotated by the drive of the packaging machine. In the wall of thebore 142 there is an annular groove 15 which communicates with a conduit12. The pipe or communication 10 extends through the body of the valve14 and terminates in communication with the cylindrical bore 142. Theplug '16 has on its periphery a groove 17 which is of such size that itconnects the mouth of the communication 10 with the annular groove 15whenever the groove 17 (during the course of the rotative movements ofthe plug 16) comes into registry with the mouth of the communication 10.

The communication 12 leads to a pressure fluid pump 11 which in theillustrated embodiment is a gear pump consisting, r'or example, of twomeshing gears which rotate in opposite directions as shown by thearrows. The pump 11 is fed from the oil supply or oil reservoir (notshown) through a filter 111.

In the communication 12 there is also provided a pressure relief valve13, which, like the safety valve 18, has been shown as a ball valve, theball I131 being pressed by a spring 132 against its valve seat. Theoutlet side of 3 the pressure relief valve 13 is connected to theconduit 19 forming part of the lubricating system of the entire machine.

The apparatus operates as follows: The eccentric disk 7, driven :intimed relation to the packaging machine, presses during its rotationagainst the roller 77 and thus moves the piston 8 on the piston rod 82against the action of the spring 81. As a result, the fluid in advanceof the piston is caused to flow through the conduits 5 and 4 to thecylinders 2 whereby the sealing jaws 1 are brought together into aclosed relationship. The springs 3 are so chosen that the fluid pressureagainst the pistons 22 is great enough to overcome the pressure of thesprings 3. When the piston S in cylinder 6 has reached its lowest pointof movement, the continued rotation of the disk 7 results in a returnmovement of the piston 8 under the influence of the spring 81. However,because of the inertia of the pressure fluid in the conduits 4 and 5, areduced pressure temporarily manifests itself in cylinder 6. Inaccordance with the invention, at this instant of time the rotating plug16 of the regulating valve 14 (which, like the pressure pump 6, isdriven in timed relation to the packaging machine) will have rotated toa point at which the groove 17 establishes communication between theconduits 10 and 12 and thus with pump 11. As a result, pressure fluidflows through the conduit 12 and through the regulating valve 14 to andthrough the conduit 10 into the cylinder 6. Since the capacity of thecylinder 6 corresponds exactly to the combined capacity of the cylinders2 and the pressure regulating unit 9, an excess of pressure fluid existsin the system 2, 4, 5, 9 and 10 at the end of the return stroke of thepiston 8. The curvature of the eccentric disk 7 is of such characterthat the piston 8 remains for a short period of time at its uppermostposition. As a result, it is possible during this short period of timefor the excess fluid, under the action of the springs 3, to flow ofithrough the regulating valve 14, the movements of the plug 16 being soregulated that the groove 17 still connects the conduits 10 and 12. Atthe conclusion of this procedure, the connection between the conduits1t) and 12 is broken off by further rotation of the plug 16, and thepump 11 thereupon delivers oil through the pressure relief valve 13 intothe lubricating system 19. The auxiliary pump 11 thus serves also as apressure pump for the lubricating system of the packaging machine.

The ability quickly and temporarily to introduce added fluid into thepump chamber 6 at the instant of commencement of each return stroke ofthe piston 8 results in all-owing the packaging machine to be operatedmuch more rapidly.

In a preferred embodiment of the invention the springs 3, 92, 132, and182 are so chosen that the force of the springs 3 upon the pressurefluid is in the region of 6 atmospheres in the cylinders 2, the force ofthe spring 92 is such as to transmit to the piston 93 and thus to thepressure fluid in the conduits 4 and 5 a pressure of from 10 toatmospheres, the valve 13 opens under an excess pressure of 2atmospheres, and the safety valve 18 opens under an excess ressure ofatmospheres.

What is claimed is:

1. In a packaging machine in which a tube of packaging material is drawnbetween a pair of sealing jaws, the jaws being movable toward each otherto clamp the tube between them and produce a transverse seal in thetube, and away from each other to release the tube:

hydraulic apparatus for controlling said movements of said jawscomprising a piston-cylinder device allocated to each of said jaws, saidjaws being connected to the pistons of their respective devices, apiston pump communicating with said cylinders through a conduit, meansfor moving the piston of said pump through alternate pressure andsuction strokes, a regulating valve, an auxiliary pump adapted tocommunicate with said piston pump through said regulating valve, andmeans for controlling said regulating valve to establish communicationbetween said auxiliary pump and piston pump only during the suctionstroke of said piston pump.

2. In a packaging machine, the elements defined in claim 1 including apressure control valve communicating with the conduit connecting saidpiston pump and piston-cylinder devices.

3. In a packaging machine, the elements defined in claim I wherein saidregulating valve comprises a body having a cylindrical bore, a plugrotatably mounted within said bore, said plug having a groove in itssurface, a first conduit connecting said auxiliary pump to saidregulating valve and terminating at the inner surface of said bore, andanother conduit connecting said piston pump to said regulating valve andterminating at the inner surface of said bore near the terminal of saidfirst conduit, said plug being rotatable intermittently to bring saidgroove into communication with the terminals of said conduits in theinner surface of said bore, said regulating valve control means servingto rotate said plug in timed relation to the operation of said pistonpump.

4. In a packaging machine, the elements defined in claim 3, in whichsaid bore is provided with an annular groove at the termination of saidfirst conduit, whereby said groove in the plug is in constantcommunication with the conduit leading to said auxiliary pump.

5. In a packaging machine, the elements defined in claim 3 including apressure relief valve communicating with the conduit between saidauxiliary pump and said regulating valve.

6. In a packaging machine, the elements defined in claim 3 wherein saidauxiliary pump is a gear pump.

7. In a packaging machine, the elements defined in claim 1 including asafety valve communicating with said piston pump.

8. In a packaging machine, the elements defined in claim 1 wherein thepressure fluid from said piston pump urges said jaw-carrying pistonstoward each other, and in which there are springs within said cylindersfor urging said pistons away from each other.

9. In a packaging machine, the elements defined in claim 1 including aneccentrically driven disk for moving the piston of said pump through itspressure stroke, and a follower carried by said pump piston and adaptedto be engaged by said disk.

10. In a packaging machine, the elements defined in claim 9 including aspring within said piston pump for urging said piston along its suctionstroke.

11. In a packaging machine, the elements defined in claim 5 wherein theoutlet from said pressure relief valve communicates with the lubricatingsystem of the packaging machine.

References Cited by the Examiner UNITED STATES PATENTS 2,437,821 3/1948Hughes -545 FRANK E. BAILEY, Primary Examiner. S. ABEND, AssistantExaminer.

1. IN A PACKAGING MACHINE IN WHICH A TUBE OF PACKAGING MATERIAL IS DRAWNBETWEEN A PAIR OF SEALING JAWS, THE JAWS BEING MOVABLE TOWARD EACH OTHERTO CLAMP THE TUBE BETWEEN THEM AND PRODUCE A TRANSVERSE SEAL IN THETUBE, AND AWAY FROM EACH OTHER TO RELEASE THE TUBE; HYDRAULIC APPARATUSFOR CONTROLLING SAID MOVEMENTS OF SAID JAWS COMPRISING A PISTON-CYLINDERDEVICE ALLOCATED TO EACH OF SAID JAWS, SAID JAWS BEING CONNECTED TO THEPISTONS OF THEIR RESPECTIVE DEVICES, A PISTON PUMP COMMUNUCATING WITHSAID CYLINDERS THROUGH A